Lumber is graded by application of regional grading standards, for example, the American Lumber Standards, which are based on one or more of the structural integrity, shape, dimensions, and appearance of a board. These grades take into account the sizes and locations of defects, together with the slopes of grains, shape, and dimensions to predict one or more of the load-bearing capacities and acceptable appearance of the boards. (These attributes of the boards, together with grade and trim symbols, are hereafter referred to collectively as “board attribute information.”) For several decades, board lumber scanning systems have projected onto boards and displayed on monitors board attribute information solutions including board feature and quality information. With the advent of low-cost projectors, large format televisions, and augmented reality devices, however, the possibilities for what data can be presented to check graders have increased. There is still, however, a limit to the amount of board attribute information a check grader can absorb in the short amount of time available to check a board transported on a conveyor.
It is not unusual for a check grader to roam several steps in either direction along a board conveyor to interact with a particular board of interest, but existing systems have no real time feedback capability indicating that the check grader is interacting with a specific board. Typically, the check grader can observe the solution computed by a board scanning system and then choose to override that solution by writing a mark on the board indicating that it is to be processed at a later time. The amount of board attribute information available to the check grader is, however, limited by time and space.
Existing systems can visually project the solution onto the boards for the check grader to see and effect a grade/trim override if necessary. If, in these existing systems, the check grader changes the position of a board transported by a moving conveyor, the solution overlay is projected in the wrong location, i.e., to a place where the board was, not to the place where the board has been moved.